Around overflow swimming pools a channel is built at water level or below. There are different types of overflow pools, the main ones are known under the trade names of the Finnish System and the Zurich System, the main difference being the difference in levels between the water and the channel.
To build this edging and channel in overflow pools, a system of two successive casings is often required, which owing to its particular design, is extremely complicated, because any minor deviations that usually occur to a greater or lesser extent, make it impossible to then place the ceramic parts properly or for the pool to overflow correctly.
There is a variant to the Zurich system on the market, trading under the name of Wiesbaden, which attempts to solve these problems with a ceramic part. This part is used as edging, channel and outer surface at the same time, but because it is made in ceramic, it is very expensive. Also, it must be of a very small size and it can only be applied in cases where there is limited space. These parts cannot be used for the Finnish system as they cannot provide the so-called “beach,” which is the submerged part of the swimming pool edge between the channel and the inside vertical wall.
Correcting these deviations of the edging/channel later on means significant additional labor costs, as part of the cement has to be chipped, or the inadmissible gaps have to be filled, or what is worse, the different angles needed on the edge near the channel have to be adjusted. This is the situation in the most popular of all the systems: the Finnish system.